So I've been thinking of the status of Jetman as a groundbreaking season or not. I saw some people mention the idea that it was groundbreaking because of "the romance". I disagree with that, however -- not necessarily because it was done before, but more because... well, sentai just never really went there again. At the least, romances are still mainly treated as secondary character beats, and series that contain running romance plots are really more the exception -- or at least, not prevelent enough to be called "the rule".
But I do think there's a way in which Jetman is a groundbreaking season: the pioneering of the "misfit team".
It seems to me that prior to Jetman, while teams may have had their problems, our heroes were still generally portrayed as fully trained and deserving of their status. I'm not extremely well-versed in 80s sentai, so someone more knowledgeable may correct me on this, but I take Turboranger as sort of a bellwether -- Turboranger is a series about high school students who are chosen more or less out of the blue. You might expect that the series would use this opportunity to portray a team that was unready, underqualified, or unwilling -- and yet, the series never really goes there. To the contrary, from day one, they're assured that (being young) they're the absolute best ones for the job; they accept this unconditionally, and throughout the series the Turborangers themselves are never really portrayed as anything less than hyper-competent and worthy of their responsibility.
You go forward to Jetman, and suddenly... these guys aren't supposed to be here. They don't want to be there. Kaori accepts because she's shallow and bored, Ako has to be bribed into it, Raita has to be coerced, and Gai, well, we all know how that goes. Even Ryuu, who is in some ways the archetypical square-jawed Red, is damaged to the point where we sometimes wonder if he should really be the guy at the helm. From day one, the team is just not great at this; even they are not convinced they should be doing this. But they try. And the overall arc of Jetman is about watching the whole team (particularly Gai) slowly find a way to suck it up and do the thing that only they can do.
I feel like this is the part of Jetman that really sparked something with Inoue's fellow creators. Most tellingly, its impact was almost immediate -- if you put Zyuranger and Ohranger aside, you then have the entire 90s and well into the 00s (though I haven't seen Gaoranger -- what's its deal in that regard?) acting as a cavalcade of teams that are misfits in some respect or other. Even your "destined" teams, like Kakuranger, go out of their way to play up the idea that these guys are in some way undesirable or out of their depth. Or, in cases where you do have a proper, experienced team, it's almost always counterpointed by a Red who himself is inexperienced or in some way less than ideal.
Jetman was considered controversial at the time for choosing to focus on the adult audience at the expense of what kids might find interesting, hence the almost immediate reversal of trend with Zyuranger. But the "misfit team" survived, I think, because it opens sentai up to a greater variety of character-based stories while still maintaining sentai's kid-friendly aura. Kids can relate to these teams, after all, because kids themselves are kind of misfits -- they're inexperienced, they don't always do what they're told, and people underestimate their abilities constantly... but presented with the opportunity, they can all grow into true heroes -- that is, if they want to be like their favorite sentai team, at least.
